Preparation method and usage method of a Cu-based catalyst for preparing vinyl chloride by acetylene hydrochlorination in a fixed bed

Abstract

The present invention discloses a preparation method and a use method of a Cu-based catalyst for the preparation of vinyl chloride by acetylene hydrochlorination in a fixed bed. This method adopts an "in-situ loading + pyrolysis activation" strategy. By means of the physical barrier, chemical coordination of the polymer network to the copper salt precursor during the polymerization process of vinyl monomers and the in-situ anchoring effect of the N sites in the subsequent polymer pyrolysis products on Cu atoms, the dispersion of Cu species on the surface of the carrier is significantly improved, and their agglomeration is effectively inhibited. Further modification with sulfur-containing inorganic compounds and quaternary phosphonium salt ionic liquids can further enhance the valence stability of Cu sites and effectively inhibit reaction carbon deposition, improving the long-term reaction stability of the catalyst. The present invention develops a new type of Cu-based catalyst and proposes a preparation technology. Applying this catalyst to the reaction of acetylene hydrochlorination to prepare vinyl chloride in a fixed bed has good catalytic activity and reaction stability.

Description

Technical Field

[0001] The present invention provides a preparation method and a usage method of a Cu-based catalyst for preparing vinyl chloride by acetylene hydrochlorination in a fixed bed, belonging to the fields of material synthesis and chemical catalysis. The method adopts an "in-situ loading + pyrolysis activation" strategy to achieve the stabilization and high dispersion of active metal Cu on a carbon support. Further, by adding a sulfur-containing inorganic salt and an ionic liquid as additives, the target Cu-based catalyst is obtained. Applying this catalyst to the reaction of preparing vinyl chloride by acetylene hydrochlorination in a fixed bed has good catalytic activity and stability. Background Art

[0002] Vinyl chloride is an important basic raw material for synthesizing various chemical products, mainly used for the production of polyvinyl chloride (PVC). PVC is the second largest thermoplastic resin material in the world. Due to its excellent physical and chemical properties and high mechanical properties, it is widely used in many fields such as construction, agriculture, and medical treatment. At present, the industrial production processes of vinyl chloride monomer are mainly the acetylene method and the ethylene method. Using the acetylene method as the leading process for vinyl chloride production is a characteristic of our country, which is mainly related to the special energy structure of "rich in coal, poor in oil, and scarce in gas" in our country. However, in the core catalytic step (acetylene hydrochlorination reaction) of the acetylene method process, HgCl2 is used as a catalyst, and a large amount of mercury-containing wastewater, waste gas, and waste catalyst will be generated during the reaction, seriously polluting the environment. The replacement of the mercuric chloride catalyst has become the core issue determining the sustainable development of the acetylene method PVC industry and the key issue affecting the technological improvement and industrial upgrading of the industry.

[0003] Professor Hutchings of Cardiff University in the UK first elaborated on the linear correlation between the activity of metal chloride catalysts and the electrode potential of metal cations during the study of the acetylene hydrochlorination reaction, which provided a theoretical basis for finding alternative metals to mercury. After continuous research and accumulation over the years, the current research on mercury-free catalysts mainly focuses on non-mercury noble metal catalysts such as Au, Pd, Ru, Pt, etc. with relatively high electrode potentials. However, considering the catalyst cost issue, researchers are trying to develop mercury-free catalysts with more reasonable prices. Compared with noble metals, metal Cu is inexpensive, and at the same time, the standard electrode potential of Cu is relatively high, having excellent potential for catalyzing the acetylene hydrochlorination reaction.

[0004] Patent application CN201310289144.9 discloses a catalyst supported on a nitrogen-doped carbon material, in which one or more elements of gold, copper, manganese, bismuth or potassium, either in elemental form or in compound form, are supported on the nitrogen-doped carbon material. Patent application CN201710174566.X discloses a mercury-free catalyst with copper salts and amide compounds as active components and activated carbon as the carrier. Patent application CN202210629764.1 discloses a mercury-free catalyst with copper salts and phosphorus-containing heterocyclic oxides as active components and activated carbon as the carrier. Patent CN202110108031.9 discloses an oxygen-containing polydentate ligand modified Cu-based catalyst for acetylene hydrochlorination reaction, its preparation method and application. Applying these catalysts to the gas-solid phase acetylene hydrochlorination reaction has achieved certain experimental results.

[0005] The above catalysts are all prepared by the post-loading method of impregnating Cu salts on the carbon carrier, and show certain catalytic activity in the acetylene hydrochlorination reaction. Although certain progress has been made, there are still many problems, and the reduction, agglomeration of metal species and reaction carbon deposition problems in the Cu-based catalyst have not been well solved. Summary of the Invention

[0006] Aiming at the deficiencies of the above disclosed technologies, the present invention proposes a "in-situ loading + pyrolysis activation" strategy. With the physical barrier, chemical coordination of the polymer network to the copper salt precursor and the in-situ anchoring effect of the N sites in the subsequent polymer pyrolysis products on Cu atoms, the dispersion of Cu species is greatly improved and their agglomeration is effectively inhibited. Subsequently, additives such as sulfur-containing inorganic compounds and ionic liquids are introduced to further improve the valence stability of Cu species and significantly inhibit the formation of reaction carbon deposition, thereby enhancing the activity and long-term reaction stability of the Cu-based catalyst. The technical content disclosed in the above patents is significantly different from the catalyst composition structure and preparation method proposed in the present invention.

[0007] The specific technical solutions of the present invention are as follows:

[0008] Solution 1. A preparation method of a Cu-based catalyst for preparing vinyl chloride by acetylene hydrochlorination in a fixed bed, characterized by comprising the following steps:

[0009] (1) Preparation of a copper salt-containing polymer solution: Add vinylimidazole, acrylonitrile and divinylbenzene to ethyl acetate, stir evenly to obtain a mixed solution; then add copper salt to the above-mentioned mixed solution, and stir at 40–60 °C for at least 3 h to obtain solution A; Let solution A cool naturally to room temperature, add a certain amount of azo compound as a polymerization initiator to it, and stir well to dissolve to obtain solution B; Among them, the copper salt is one or several of copper chloride, copper bromide, cuprous chloride, cuprous iodide, copper sulfate, copper nitrate, copper acetate, copper acetylacetonate.

[0010] (2) Preparation of polymer materials: Solution B was transferred to a high-pressure reactor with a polytetrafluoroethylene liner, and then a certain amount of 80-100 mesh carbon powder was added; a gradient heating process was used under stirring, firstly, the temperature was raised from room temperature to 60-65 °C at a heating rate of 1-3 °C / min to initiate the polymerization reaction, and the stirring was turned off after 1-2 h of reaction and maintained for 6-8 h; then the temperature was continued to be raised to 100-105 °C at a heating rate of 5-10 °C / min and aged for at least 6 h, and then naturally cooled to room temperature, and the block polymer obtained by the reaction was taken out and dried naturally. After drying, the sample was broken into 40-60 mesh for later use;

[0011] (3) Preparation of carbonized materials: The above polymer powder is placed in a high-temperature tube furnace and the sample is heat treated by a "low-temperature pre-oxidation + high-temperature carbonization" process. First, in a flowing air atmosphere, the sample is pre-oxidized at a heating rate of 1-3 °C / min from room temperature to 300-350 °C for 1-3 h. Then, the air is switched to a flowing inert atmosphere, and the sample is further carbonized at a heating rate of 1-3 °C / min to 600-1000 °C for 2-3 h. After completion, the sample is naturally cooled to room temperature to obtain a carbonized sample.

[0012] (4) Modification of carbonized samples: The sulfur-containing inorganic compound and the quaternary phosphonium salt ionic liquid are dissolved in deionized water, and then impregnated into the carbonized sample using an equal volume impregnation method. The impregnated sample is dried at 80-100 °C for 4-6 hours to obtain the desired Cu-based catalyst.

[0013] Scheme 2. A method for preparing a catalyst according to Scheme 1, characterized in that: in step (1), the mass ratio of vinyl imidazole, acrylonitrile, divinylbenzene to ethyl acetate is 0.15-0.3:0.075-0.15:0.05-0.2:20; the mass of the copper salt is 1%-20% of the sum of the masses of vinyl imidazole, acrylonitrile and divinylbenzene; the azo compound is one or two of azobisisobutyronitrile and azobisisoheptylnitrile, and the mass of the azo compound is 0.5%-4% of the sum of the masses of vinyl imidazole, acrylonitrile and divinylbenzene.

[0014] Scheme 3. A method for preparing a catalyst according to Scheme 1, characterized in that: in step (2), the carbon powder is one or more of wood charcoal, coconut shell charcoal, and coal carbon, and the amount of carbon powder added is 10%-30% of the sum of the mass of vinylimidazole, acrylonitrile and divinylbenzene.

[0015] Scheme 4. A method for preparing a catalyst according to Scheme 1, characterized in that: in step (3), the inert atmosphere is one or more of nitrogen, argon, and helium; the gas volume space velocity of air or the inert atmosphere is 10–40 h –1。

[0016] Embodiment 5. The method for preparing a catalyst according to Embodiment 1, characterized in that: in step (4), the sulfur-containing inorganic compound is one or more of sodium sulfite, potassium thiocyanate, sodium thiosulfate, ammonium thiosulfate, sodium sulfate, sodium sulfite, thiourea, and the quaternary phosphonium salt ionic liquid is one or more of tetraphenylphosphonium bromide, tetraphenylphosphonium chloride, tetraphenylphosphonium iodide, tetrabutylphosphonium bromide, methyl-triphenylphosphonium bromide, and the molar ratio of the copper salt, the sulfur-containing inorganic compound to the quaternary phosphonium salt ionic liquid is 1.0:0.05–1.0:0.5–1.0.

[0017] Embodiment 6. A Cu-based catalyst for the preparation of vinyl chloride by acetylene hydrochlorination in a fixed bed, characterized in that it is prepared by using the preparation method described in any one of Embodiments 1–5.

[0018] Embodiment 7. A method for using the Cu-based catalyst described in Embodiment 6, specifically characterized by including the following steps:

[0019] (1) Place the catalyst in a fixed-bed reactor, heat it to 100–180 °C under a flowing nitrogen atmosphere and keep it at a constant temperature for at least 1 h, wherein the volume space velocity of nitrogen is 15–45 h –1 ;

[0020] (2) Close the nitrogen and switch to flowing hydrogen chloride gas, and keep it at a constant temperature for at least 1 h, wherein the volume space velocity of hydrogen chloride is 15–45 h –1 ;

[0021] (3) After adjusting the reactor temperature to 100–240 °C, introduce acetylene gas, and the volume space velocity of acetylene is 15–250 h –1 , and control the molar ratio of hydrogen chloride to acetylene to be 1.05–1.3:1;

[0022] (4) Use gas chromatography to quantitatively analyze the gas after the reaction

[0023] Compared with the prior art, the present invention has the following significant innovations compared with the prior art:

[0024] (1) The present invention proposes an "in-situ loading + pyrolysis activation" strategy. The copper salt precursor is introduced at the initial stage of polymerization, and with the coordination of vinylimidazole and the copper salt, the ultra-high dispersion of copper species is achieved. Further pyrolyze the polymer containing the copper salt, and with the in-situ anchoring of the heteroatom N sites to the Cu atoms during the pyrolysis process, the dispersion of Cu species is greatly improved and its agglomeration is effectively inhibited. Compared with the conventional post-loading scheme, the metal loading of this in-situ loading strategy is more uniform and the structure is more stable.

[0025] (2) In the polymerization stage, we selected a high-pressure reactor with a polytetrafluoroethylene lining as the reaction vessel. After adding carbon powder, the reaction was initiated and explosively polymerized in a sealed environment at 60–65 °C. In a short period of time, the copper salt precursor was blocked in the high-density polymer network, significantly improving the dispersion of Cu species. Further, the polymer network was aged at 100–105 °C to increase the degree of polymerization and enhance the structural strength of the material, which helped to maintain the porous framework structure of the material during the subsequent heat treatment process. In this process, the addition of carbon powder played a dual role in improving the physical barrier and structural strength of the polymer.

[0026] (3) In the material heat treatment stage, we adopted the process of "low-temperature pre-oxidation + high-temperature carbonization". In the low-temperature (300–350 °C) pre-oxidation stage, an air atmosphere was selected. The main task of this stage was to transform the chain-like structural units (mainly the cyano part) in the polymerization system into a more stable six-membered aromatic ring structure through chemical processes such as intermolecular cyclization and dehydration, while exposing a large number of pyridine N sites; in the high-temperature (600–1000 °C) carbonization stage, an inert atmosphere was selected. The main task of this stage was to further modify the functional groups of the product obtained in the pre-oxidation step, remove the residual structural oxygen groups, and complete the condensation between molecular chains. Most importantly, the pyridine N sites could achieve in-situ anchoring of most Cu species, significantly improving the dispersion of Cu and effectively inhibiting its agglomeration. In addition, in addition to the N sites participating in anchoring Cu atoms, there were a large number of free N sites in the carbonization product, and these sites could also serve as adsorption and activation sites for acetylene / hydrogen chloride molecules, thereby regulating the performance of the Cu catalyst.

[0027] (4) The above Cu catalyst was further modified with a sulfur-containing inorganic compound and a phosphonium salt ionic liquid. The sulfur-containing inorganic compound could further coordinate with the Cu species on the carrier surface, improving the stability of the metal sites and effectively inhibiting the reduction and agglomeration of Cu sites during high-temperature reactions; the phosphonium salt ionic liquid could regulate the chemical environment around the metal Cu sites, enhancing its adsorption of hydrogen chloride molecules, reducing the adsorption of acetylene / vinyl chloride molecules, and inhibiting the formation of reaction coke, thereby effectively improving the reaction stability of the Cu catalyst. Description of the Drawings

[0028] Figure 1 : TEM image of the Cu-based catalyst Cat-1 prepared in Example 1. Detailed Description of the Invention

[0029] To better illustrate this patent, the following examples are listed. The following examples are to enable those in the industry to understand the present invention in more detail, or to make some non-essential improvements and adjustments based on the content of the present invention. However, the scope of the present invention is not limited by these examples.

[0030] To better illustrate this patent, the following examples are listed. The following examples are intended to enable the industry personnel to understand the present invention in more detail, or to make some non-essential improvements and adjustments based on the content of the present invention. However, the scope of the present invention is not limited by these examples. Example

[0031] (1) Vinylimidazole, acrylonitrile and divinylbenzene were added to ethyl acetate and stirred evenly; then copper chloride was added thereto and stirred at 50 °C for 3 h to obtain a blue-green transparent solution A; solution A was naturally cooled to room temperature, azobisisobutyronitrile was added thereto as an initiator, and the solution was fully stirred and dissolved to obtain a transparent solution B; wherein the mass ratio of vinylimidazole, acrylonitrile, divinylbenzene to ethyl acetate was 0.15:0.10:0.085:20; the mass of copper chloride was 10% of the sum of the mass of vinylimidazole, acrylonitrile and divinylbenzene; the mass of azobisisobutyronitrile was 1.6% of the sum of the mass of vinylimidazole, acrylonitrile and divinylbenzene;

[0032] (2) Solution B was transferred to a high-pressure reactor with a polytetrafluoroethylene liner, and 80-100 mesh coconut shell activated carbon powder was added to the solution. The suspension was placed in an electric heated blast drying oven with magnetic stirring. A gradient heating process was used under stirring. First, the temperature was raised from room temperature to 60 °C (heating rate 1 °C / min) to initiate the polymerization reaction. After 1 h of reaction, the stirring was turned off and the temperature was maintained for another 6 h. The temperature was further raised to 100 °C (heating rate 5 °C / min) for aging for 6 h. After the reaction was completed, the system was cooled naturally. The block polymer obtained by the reaction was taken out and dried naturally. After drying, the sample was crushed into 40-60 mesh for later use. The amount of carbon powder added was 15% of the sum of the mass of vinylimidazole, acrylonitrile and divinylbenzene.

[0033] (3) The powder sample was placed in a high-temperature tube furnace and heated from room temperature to 300 °C (heating rate 2 °C / min) in an air atmosphere for pre-oxidation treatment of the sample for 1 h. The air was then switched to argon and the temperature was further raised to 700 °C (heating rate 1 °C / min) for carbonization treatment of the sample for 3 h. After the heat treatment was completed, the sample was naturally cooled to room temperature. The air and argon gas space velocity was 15 h / min. –1 ;

[0034] (4) Sodium thiosulfate and methyl triphenylphosphonium bromide were dissolved in deionized water, and the solution was impregnated into the carbonized sample by an equal volume impregnation method. The impregnated sample was air-dried at room temperature and then dried at 100 °C for 6 h to obtain the target Cu-based catalyst, which was numbered Cat-1. The molar ratio of copper salt, sodium thiosulfate and methyl triphenylphosphonium bromide was 1.0:0.2:0.5. Example

[0035] The catalyst preparation steps of Example 2 are the same as those of Example 1, except that copper chloride in step (1) is modified to copper acetylacetonate, and the obtained Cu catalyst is numbered Cat-2. Example

[0036] The catalyst preparation steps of Example 3 are the same as those of Example 1, except that the mass ratio of vinylimidazole, acrylonitrile, divinylbenzene to ethyl acetate in step (1) is modified from 0.15:0.10:0.085:20 to 0.15:0.075:0.085:20, and the obtained Cu catalyst is numbered Cat-3. Example

[0037] The catalyst preparation steps of Example 4 are the same as those of Example 1, except that the initiator azobisisobutyronitrile in step (1) is modified to azodiisooctanenitrile, and the obtained Cu catalyst is numbered Cat-4. Example

[0038] The catalyst preparation steps of Example 5 are the same as those of Example 1, except that coconut shell activated carbon in step (2) is modified to bituminous coal activated carbon, and the obtained Cu catalyst is numbered Cat-5. Example

[0039] The catalyst preparation steps of Example 6 are the same as those of Example 1, except that the addition amount of carbon powder in step (2) is modified from 15% of the sum of the masses of vinylimidazole, acrylonitrile and divinylbenzene to 30%, and the obtained Cu catalyst is numbered Cat-6. Example

[0040] The catalyst preparation steps of Example 7 are the same as those of Example 1, except that the air pre-oxidation temperature in step (3) is modified from 300 °C to 350 °C, and the obtained Cu catalyst is numbered Cat-7. Example

[0041] The catalyst preparation steps of Example 8 are the same as those of Example 1, except that the carbonization temperature in step (3) is modified from 700 °C to 600 °C, and the obtained Cu catalyst is numbered Cat-8. Example

[0042] The catalyst preparation steps of Example 9 are the same as those of Example 1, except that the carbonization temperature in step (3) is modified from 700 °C to 1000 °C, and the obtained Cu catalyst is numbered Cat-9. Example

[0043] The catalyst preparation steps of Example 10 are the same as those of Example 1, except that the air gas hourly space velocity in step (3) is modified from 15 h –1 to 40 h –, the obtained Cu catalyst is numbered Cat-10. Example

[0044] The catalyst preparation steps of Example 11 are the same as those of Example 1, except that the molar ratio of copper salt, sodium thiosulfate and methyl-triphenylphosphonium bromide in step (4) is modified from 1.0:0.2:0.5 to 1.0:0.05:0.5. The obtained Cu catalyst is numbered Cat-11. Example

[0045] The catalyst preparation steps of Example 12 are the same as those of Example 1, except that sodium thiosulfate in step (4) is modified to potassium thiocyanate. The obtained Cu catalyst is numbered Cat-12. Example

[0046] The catalyst preparation steps of Example 13 are the same as those of Example 1, except that methyl-triphenylphosphonium bromide in step (4) is modified to tetrabutylphosphonium bromide. The obtained Cu catalyst is numbered Cat-13.

[0047] Comparative Example 1

[0048] The polymerization monomer components are changed, aiming to compare with Example 1 to illustrate the influence of the change of polymerization monomers on the dispersion of metal Cu in the catalyst and its catalytic performance.

[0049] The preparation steps of Comparative Example 1 are the same as those of Example 1, except that vinyl imidazole in step (1) is removed. The obtained Cu catalyst is numbered Cat-14.

[0050] Comparative Example 2

[0051] The polymerization monomer components are changed, aiming to compare with Example 1 to illustrate the influence of the change of polymerization monomers on the dispersion of metal Cu in the catalyst and its catalytic performance.

[0052] The preparation steps of Comparative Example 2 are the same as those of Example 1, except that acrylonitrile in step (1) is removed. The obtained Cu catalyst is numbered Cat-15.

[0053] Comparative Example 3

[0054] The amount of initiator azobisisobutyronitrile is reduced, aiming to compare with Example 1 to illustrate the influence of the initiator amount on the polymer structure.

[0055] The preparation steps of Comparative Example 3 are the same as those of Example 1, except that the mass of azobisisobutyronitrile in step (1) is modified from 1.6% of the sum of the masses of vinyl imidazole, acrylonitrile and divinylbenzene to 0.5%. The obtained Cu catalyst is numbered Cat-16.

[0056] Comparative Example 4

[0057] No coconut shell activated carbon powder is added, aiming to make a comparison with Example 1 to illustrate the influence of the addition or not of carbon powder on the polymerization reaction process and the polymer yield.

[0058] The preparation steps of Comparative Example 4 are the same as those of Example 1, except that the step of adding coconut shell activated carbon powder in step (2) is removed, and the obtained Cu catalyst is numbered Cat-17.

[0059] Comparative Example 5

[0060] The pre-oxidation treatment temperature of the polymer material is increased, aiming to make a comparison with Example 1 to illustrate the influence of the pre-oxidation temperature on the structure and performance of the catalyst.

[0061] The preparation steps of Comparative Example 5 are the same as those of Example 1, except that the pre-oxidation temperature in air atmosphere in step (3) is modified from 300 °C to 400 °C, and the obtained Cu catalyst is numbered Cat-18.

[0062] Comparative Example 6

[0063] The carbonization temperature of the polymer material is increased, aiming to make a comparison with Example 1 to illustrate the influence of the carbonization temperature on the spatial / geometric distribution of Cu species in the catalyst and its catalytic performance.

[0064] The preparation steps of Comparative Example 6 are the same as those of Example 1, except that the carbonization temperature in argon atmosphere in step (3) is modified from 700 °C to 1200 °C, and the obtained Cu catalyst is numbered Cat-19.

[0065] Comparative Example 7

[0066] The gas volume space velocity of the pre-oxidation / carbonization atmosphere is increased, aiming to make a comparison with Example 1 to illustrate the influence of the gas space velocity of the heat treatment atmosphere on the structure and catalytic performance of the catalyst.

[0067] The preparation steps of Comparative Example 7 are the same as those of Example 1, except that the gas space velocities of air and argon in step (3) are modified from 15 h –1 to 60 h –1 , and the obtained Cu catalyst is numbered Cat-20.

[0068] Comparative Example 8

[0069] No sulfur-containing inorganic compound is added as an auxiliary agent, aiming to make a comparison with Example 1 to illustrate the influence of the addition of sodium thiosulfate on the stability of Cu sites in the catalyst.

[0070] The preparation steps of Comparative Example 8 are the same as those of Example 1, except that the step of adding sodium thiosulfate in step (4) is removed, and the obtained Cu catalyst is numbered Cat-21.

[0071] Comparative Example 9

[0072] The phosphonium salt ionic liquid is not added as an additive, aiming to compare with Example 1 to illustrate the influence of the addition of the phosphonium salt ionic liquid on the reaction carbon deposition of the catalyst.

[0073] The preparation steps of Comparative Example 9 are the same as those of Example 1, except that the addition step of methyl-triphenylphosphonium bromide in step (4) is removed, and the obtained Cu catalyst is numbered Cat-22.

[0074] Comparative Example 10

[0075] The introduction order of the copper salt is changed, aiming to compare with Example 1 to illustrate the influence of the in-situ loading / post-loading introduction scheme of the copper salt on the catalyst performance.

[0076] The preparation steps of Comparative Example 10 are the same as those of Example 1, except that the addition step of copper chloride is adjusted from step (1) to step (4), and the obtained Cu catalyst is numbered Cat-23.

[0077] The evaluation process and conditions of the catalyst are as follows:

[0078] (1) Place the catalyst in a fixed-bed reactor, heat it to 160 °C under a flowing nitrogen atmosphere and keep it at a constant temperature for 1 h, where the volume space velocity of nitrogen is 30 h –1 ;

[0079] (2) Close the nitrogen and switch to flowing hydrogen chloride gas, and keep it at a constant temperature for 1 h, where the volume space velocity of hydrogen chloride is 30 h –1 ;

[0080] (3) Introduce acetylene gas, the volume space velocity of acetylene is 50 h –1 , and the molar ratio of hydrogen chloride to acetylene is 1.2:1;

[0081] Use gas chromatography to quantitatively analyze the gas after the reaction, sample once every 0.5 h, select the point of 1.5 h of reaction as the initial activity data, and calculate the deactivation rate according to the 10 h continuous reaction data. The acetylene hydrochlorination reaction performance data of different Cu catalysts are shown in the table:

[0082] Catalyst Number Acetylene Conversion Rate (%) Vinyl Chloride Selectivity (%) <![CDATA[Deactivation rate (% h –1 )]]> Cat-1 96.3 99.8 0.03 Cat-2 92.5 99.7 0.12 Cat-3 93.3 99.5 0.21 Cat-4 92.4 99.2 0.23 Cat-5 95.8 99.7 0.05 Cat-6 83.4 99.3 0.04 Cat-7 92.1 99.5 0.13 Cat-8 90.1 99.1 0.19 Cat-9 83.7 99.4 0.32 Cat-10 89.1 99.6 0.09 Cat-11 97.1 99.5 0.05 Cat-12 94.1 99.4 0.22 Cat-13 95.6 99.7 0.03 Cat-14 82.2 99.5 0.32 Cat-15 65.8 99.4 1.56 Cat-16 70.8 99.6 2.49 Cat-17 83.6 99.5 0.16 Cat-18 65.3 99.8 3.47 Cat-19 52.4 99.2 4.52 Cat-20 92.3 99.8 5.11 Cat-21 97.3 99.2 1.03 Cat-22 96.2 99.6 1.52 Cat-23 87.5 99.3 0.48

Claims

1. A preparation method of a Cu-based catalyst for preparing vinyl chloride by acetylene hydrochlorination in a fixed bed, characterized in that It includes the following steps: (1) Preparation of a copper salt-containing polymerization solution: Add vinylimidazole, acrylonitrile, and divinylbenzene to ethyl acetate, and stir evenly to obtain a mixed solution; then add a copper salt to the aforementioned mixed solution, and stir at 40–60 °C for at least 3 h to obtain solution A; Naturally cool solution A to room temperature, add a certain amount of azo compound as a polymerization initiator thereto, and stir well to dissolve to obtain solution B; wherein, the copper salt is one or more of copper chloride, copper bromide, cuprous chloride, cuprous iodide, copper sulfate, copper nitrate, copper acetate, and copper acetylacetonate; (2) Preparation of the polymer material: Transfer solution B to a high-pressure reactor with a polytetrafluoroethylene liner, and then add a certain amount of 80–100 mesh carbon powder; under a stirring state, adopt a gradient heating process. First, heat from room temperature to 60–65 °C at a heating rate of 1–3 °C / min to initiate the polymerization reaction. After reacting for 1–2 h, turn off the stirring and keep it for 6–8 h; then continue to heat to 100–105 °C at a heating rate of 5–10 °C / min for aging for at least 6 h, and then naturally cool to room temperature. Take out the obtained bulk polymer and dry it naturally. After drying, crush the sample to 40–60 mesh for standby; (3) Preparation of the carbonized material: Place the above polymer powder in a high-temperature tubular furnace, and perform heat treatment on the sample by adopting a "low-temperature pre-oxidation + high-temperature carbonization" process. First, under a flowing air atmosphere, heat the sample from room temperature to 300–350 °C at a heating rate of 1–3 °C / min for pre-oxidation treatment, and the pretreatment time is 1–3 h; then switch the air to a flowing inert atmosphere, and further heat to 600–1000 °C at a heating rate of 1–3 °C / min for carbonization treatment of the sample. The carbonization time is 2–3 h. After completion, naturally cool to room temperature to obtain a carbonized sample; (4) Modification and decoration of the carbonized sample: Dissolve a sulfur-containing inorganic compound and a phosphonium salt ionic liquid in deionized water, and impregnate the above carbonized sample by the equal-volume impregnation method. Dry the impregnated sample at 80–100 °C for 4–6 hours to obtain the required Cu-based catalyst.

2. The preparation method of the catalyst according to claim 1, wherein: In step (1), the mass ratio of vinylimidazole, acrylonitrile, divinylbenzene to ethyl acetate is 0.15–0.3:0.075–0.15:0.05–0.2:20; the mass of the copper salt is 1%–20% of the sum of the masses of vinylimidazole, acrylonitrile, and divinylbenzene; the azo compound is one or two of azobisisobutyronitrile and azodiisooctanenitrile, and the mass of the azo compound is 0.5%–4% of the sum of the masses of vinylimidazole, acrylonitrile, and divinylbenzene.

3. The preparation method of the catalyst according to claim 1, wherein: In step (2), the carbon powder is one or more of wood charcoal, coconut shell charcoal, and coal-based carbon, and the addition amount of the carbon powder is 10%–30% of the sum of the masses of vinylimidazole, acrylonitrile, and divinylbenzene.

4. The preparation method of the catalyst according to claim 1, wherein: In step (3), the inert atmosphere is one or more of nitrogen, argon, and helium; the gas hourly space velocity of air or the inert atmosphere is 10–40 h –1 .

5. The preparation method of the catalyst according to claim 1, characterized in that: In step (4), the sulfur-containing inorganic compound is one or more of sodium sulfite, potassium thiocyanate, sodium thiosulfate, ammonium thiosulfate, sodium sulfate, sodium sulfite, and thiourea, and the quaternary phosphonium salt ionic liquid is one or more of tetraphenylphosphonium bromide, tetraphenylphosphonium chloride, tetraphenylphosphonium iodide, tetrabutylphosphonium bromide, and methyl-triphenylphosphonium bromide. The molar ratio of the copper salt, the sulfur-containing inorganic compound to the quaternary phosphonium salt ionic liquid is 1.0:0.05–1.0:0.5–1.

0.

6. A Cu-based catalyst for the preparation of vinyl chloride by acetylene hydrochlorination in a fixed bed, characterized in that, Prepared by using the preparation method according to any one of claims 1–5.

7. A method for using the Cu-based catalyst according to claim 6, which specifically comprises the following steps: (1) Place the catalyst in a fixed-bed reactor, heat it to 100–180 °C under a flowing nitrogen atmosphere and keep it at a constant temperature for at least 1 h, where the volume space velocity of nitrogen is 15–45 h –1 ; (2) Close the nitrogen and switch to flowing hydrogen chloride gas, and keep the temperature constant for at least 1 h, where the volume space velocity of hydrogen chloride is 15–45 h –1 ; (3) After adjusting the reactor temperature to 100–240 °C, acetylene gas is introduced, and the acetylene volume space velocity is 15–250 h –1 , and the molar ratio of hydrogen chloride to acetylene is controlled to be 1.05–1.3:1; (4) Quantitative analysis of the gas after the reaction is carried out by using gas chromatography.

Images